Photoluminescent hybrid organic/inorganic materials and method for preparing same

ABSTRACT

Disclosed is a method for preparing a hybrid organic/inorganic composition including inorganic nanoparticles functionalized by at least one molecule chosen from photoluminescent charged organic molecules, the method including bringing into contact, in a single-phase solvent medium, at least one photoluminescent charged organic molecule and non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm. Also disclosed are hybrid photoluminescent nanoparticles compositions obtained by this method.

The present invention relates to non-swelling synthetic nano-scaleinorganic fillers of phyllosilicates (lamellar silicates) type such as,for example, talc, mica, kaolinite, on which charged organicphotoluminescent compounds are adsorbed. The invention also relates to amethod for the preparation of these fillers and their uses.

PRIOR ART

Organic compounds colored in the visible or photoluminescent compounds(fluorescent or phosphorescent compounds that absorb UV or visible lightand then re-emit this energy in light form) are known for manyapplications, especially for the marking and detection of materials.with which they are associated. These may be materials such as polymers,mineral particles, glasses, etc. Applications for such materials arealso known in the fields of catalysis or papermaking.

However, some photoluminescent organic compounds may be degraded underconditions in which they are implemented and their properties reduced.Labeling with photoluminescent compounds usually requires the formationof a covalent bond between the compound to be labeled and thephotoluminescent organic molecule. Such a step is often complicated andexpensive, while being liable to modify the behavior of the labeledparticle. While certain natural talcs (steatites) have various colorssuch as pink, gray or green, when they are in the form of blocks asobtained directly after extraction, their grinding into fine particles(between 2 and 200 μm) irreparably leads to obtaining white to greyishpowders, the color of the natural talc being solely due to specificarrangements of talc particles relative to each other. The grinding ofsuch natural talcs thus irreparably leads to a loss of the initialnatural pinkish or greenish coloration of the talc.

Mineral particles functionalized by at least one organic group or“organic/inorganic hybrid particles” are of increasing interest invarious fields of chemistry, due to their ability to combine certainadvantages of both organic compounds and inorganic compounds. Thecreation of strong interactions between organic and inorganic compoundsallows long-term immobilization of organic species on inorganiccompounds, providing the organic species with the structural order ofthe inorganic compounds.

WO2014/049250 describes the combination of silicate mineral particlesand coloring molecules to give colored silicate particles. The coloringmolecules used in this document are metal cations. Metal salts oftransition metals adsorbed on nanometric phyllosilicates give themcoloring, but of lower intensity than with organic dyes.

The metal salts have a different behavior from the organic molecules,their respective properties not being extrapolatable from one family ofcompounds to another. For example, virtually no adsorption of metalsalts on micron-sized phyllosilicates is observed, whereas chargedorganic colored molecules may be partially adsorbed on micron-sizedphyllosilicates. However, the inventors have surprisingly found a muchgreater adsorption of photoluminescent charged organic molecules onnanometric phyllosilicates compared to micrometric phyllosilicates.

WO2014/207397 describes a method for the preparation of a compositioncomprising functionalized mineral particles, in which a phyllosilicatecomposition comprising mineral particles belonging to the family oflamellar silicates is brought into contact with a solution comprising awater-soluble functionalization agent selected from the group consistingof oxysilanes and oxygermanes having at least one organic group. Thismethod requires a step of functionalization of the organic group with anoxysilane and/or an oxygen carrier. The hybrid organic-inorganicmaterials thus obtained do not make it possible to achieve satisfactorygrafting rates.

As another alternative to the preparation of organic/inorganic hybrids,methods of direct synthesis of such materials by sol-gel route are alsoknown. However, these materials have very low crystalline properties andstructural properties very far from those of natural or syntheticnon-hybrid phyllosilicates. In addition, these sol-gel syntheses can notgenerally be carried out in an aqueous medium.

Document WO2014/202920 discloses a method for preparing a compositioncomprising silico/germano-metallic mineral particles functionalized byat least one organic group in which a hydrothermal treatment of ahydrogel precursor of the silico/germano-metallic mineral particles iscarried out. The method is characterized in that a hydrogel comprisingsilico/germano-metallic particles functionalized with at least oneorganic group is used.

Prior art is known from V. M. Martinez, Langmuir 2004, 20, 5709-5717, inthe case of hybrid materials based on clay and Rhodamine 6G. Unlike theinvention, the clays used are swelling materials. The intercalation ofRhodamine 6G or other dyes in swelling clay occurs through a cationexchange mechanism between the hydrated interfoliar cation(s) of theswelling clay and the organic molecule. The non-swelling phyllosilicatesare characterized either by a non-cationic interface space (for exampletalc or kaolinites), or by the presence in the interfoliar space ofnon-hydrated cations (for example in the case of micas). Unlike swellingclays, it is not possible to intercalate charged molecules in theinterfoliar space of non-swelling phyllosilicates by cation exchange.

Compositions comprising synthetic nanotalc and cosmetic active agents,for example UV filters, are known from WO2016/083404. Compositionscomprising synthetic nanotalc and electrolytic or polyelectrolytic typecosmetic active ingredients are known from WO2016/083418. However, theseactive ingredients are not photoluminescent molecules. Moreover, thesedocuments do not mention the capacity of charged photoluminescentmolecules to be irreversibly adsorbed on a synthetic nanotalc.

Rahman A. et al., Water and Environment Journal 29 (2015) 375-382describes the use of natural or synthetic clay particles to removeanionic dyes from a medium. The intended application is the depollutionof effluents from textile industries. The materials used are micrometricand have low crystallinity.

The aim of the invention is to provide a method for preparing, in asimple and rapid manner, a composition comprising silicate mineralparticles having photoluminescence properties.

The invention also aims at providing a method for preparing acomposition comprising phyllosilicate mineral particles, the particleshaving photoluminescence properties that are not only modulableaccording to the desired shade and intensity of the color but also thatare durable and stable over time, from a composition comprisingphyllosilicate mineral particles already synthesized.

Such a composition capable of acting as both functional mineral fillerand photoluminescent pigment, is of major interest in many fields, suchas those of optical brighteners, biology, cosmetics or even mineralfillers for paints, polymers, optical materials, biological labeling, aswell as inks. Such compositions may also be used as filler in thepapermaking composition.

The invention aims to provide a method whose implementation is simpleand fast, and is compatible with the constraints of an industrialoperation.

The object of the invention is also to propose a method for preparing awide chemical diversity of compositions comprising mineral particles ofstructure and properties similar to those of talcs, micas or naturalkaolinites, and whose photoluminescence properties may be easilycontrolled and modified.

The ability of phyllosilicate nanoparticles to irreversibly bind chargedphotoluminescent organic molecules may also be used to extractphotoluminescent compounds from a medium.

SUMMARY OF THE INVENTION

A first object of the invention relates to a method for preparing anorganic/inorganic hybrid composition comprising mineral nanoparticlesfunctionalized by at least one molecule chosen from photoluminescentcharged organic molecules, this method comprising at least bringing intocontact, in a monophasic solvent medium, at least one photoluminescentcharged organic molecule and non-swelling phyllosilicate nanoparticleshaving a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to10 μm.

According to a preferred embodiment, the method comprises at least thefollowing steps:

-   -   (i) providing a solution (a) of at least one photoluminescent        charged organic molecule in at least one solvent,    -   (ii) providing a suspension (b) of non-swelling phyllosilicate        nanoparticles in at least one solvent,    -   (iii) contacting the solution (a) and the suspension (b).

According to an advantageous embodiment, the method further comprisesthe following steps:

-   -   Elimination of the solvent phase,    -   Recovery of nanoparticles.

According to a preferred embodiment, the solvent of the solution (a) andthe solvent of the suspension (b) are miscible.

The invention also relates to a composition of hybrid nanoparticlescomprising at least one non-swelling phyllosilicate and at least onemolecule chosen from photoluminescent charged organic molecules, saidorganic molecule being adsorbed on the phyllosilicate, this compositionbeing capable of being obtained by the method according to the inventionas described above and in detail below.

According to a preferred embodiment, the non-swelling phyllosilicatenanoparticles have a particle size ranging from 1 nm to 10 μm.

According to a preferred embodiment, the non-swelling phyllosilicatenanoparticles have a thickness of between 1 nm and 100 nm, and a largerdimension between 10 nm and 10 μm.

According to a preferred embodiment, the non-swelling phyllosilicatesare chosen from talc, micas, kaolinites and mixtures thereof.

According to a preferred embodiment, the non-swelling phyllosilicateshave the following chemical formula:(Si_(x)Ge(1−x))₄M₃O₁₀(OH)₂,  (I)

in which:

-   -   x is a real number of the interval [0; 1],    -   M denotes at least one divalent metal having the formula    -   Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each        index yi representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸yi=1.

According to another preferred embodiment, the non-swellingphyllosilicates have the following chemical formula:(Aly′M′(1−y′))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II)

in which:

-   -   M′ denotes at least one trivalent metal chosen from the group        consisting of gallium and rare earths,    -   y′ is a real number of the interval [0; 1],    -   x′ is a real number of the interval [0; 1].

According to yet another preferred embodiment, the non-swellingphyllosilicates have the following chemical formula:At(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III)

in which:

-   -   A denotes at least one monovalent cation of a metal element        having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), each wi        representing a real number of the interval [0; 1] such that        Σ_(i=1) ⁵=1.    -   x″ is a real number of the interval [0; 1],    -   M″ denotes at least one divalent metal having the formula        Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each        index ji representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸ji=1,    -   k is a real number in the range [2.50; 2.85]    -   t+2k is a real number of the interval [5.3; 6.0].

According to a preferred embodiment, the non-swelling phyllosilicatesare formed of a stack of elementary sheets of 2:1 phyllosilicate typeand correspond to the following chemical formula:(SixGe(1−x))₄M₃O₁₀(OH)₂,  (I)

in which:

-   -   x is a real number of the interval [0; 1],    -   M denotes at least one divalent metal having the formula        Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each        index yi representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸yi=1.

According to another preferred embodiment, the non-swellingphyllosilicates are formed of a stack of phyllosilicate elementarysheets 1:1 and correspond to the following chemical formula:(Aly′M′(1−y′))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II)

in which:

-   -   M′ denotes at least one trivalent metal chosen from the group        consisting of gallium and rare earths,    -   y′ is a real number of the interval [0; 1],    -   x′ is a real number of the interval [0; 1].

According to yet another preferred embodiment, the non-swellingphyllosilicates are formed of a stack of elementary sheets of 2:1phyllosilicate type and correspond to the following chemical formula:At(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III)

in which:

-   -   A denotes at least one monovalent cation of a metal element        having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), each wi        representing a real number of the interval [0; 1] such that        Σ_(i=1) ⁵wi=1.    -   x″ is a real number of the interval [0; 1],    -   M″ denotes at least one divalent metal having the formula        Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each        index ji representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸ji=1,    -   k is a real number in the range [2.50; 2.85]    -   t+2k is a real number of the interval [5.3; 6.0].

According to a still more preferred embodiment, the non-swellingphyllosilicates are formed of a stack of elementary sheets:

-   -   of phyllosilicate type 2:1 and of chemical formula        Si₄M₃O₁₀(OH)₂, more particularly of chemical formula        Si₄Mg₃O₁₀(OH)₂.

According to a still preferred embodiment, the non-swellingphyllosilicates are formed of a stack of elementary sheets:

-   -   Phyllosilicate type 1:1 and chemical formula Al₂Si₂O₅(OH)₄.

According to a still more preferred embodiment, the non-swellingphyllosilicates are formed of a stack of elementary sheets:

-   -   of phyllosilicate type 2:1 and chemical formula        KSi₄Mg_(2.5)O₁₀(OH)₂ (IIId) or K_(0.8)Si₄Mg_(2.6)O₁₀(OH)₂        (IIIf).

According to one embodiment, the photoluminescent organic molecule ischosen from those having an absorption in the ultraviolet (wavelengthranging from 200 to 380 nm) or the visible (wavelength ranging from 380to 780 nm) range, and re-emitting the energy absorbed in light form.

According to one embodiment, the solution (a) further comprises at leastone charged colored organic molecule chosen from those having anabsorption in the visible range (wavelength ranging from 380 to 780 nm).

According to a still more preferred embodiment, the photoluminescentorganic molecule is chosen from:

-   -   Rhodamine B, or        [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium        chloride—or any other form of Rhodamine B such as, for example,        Rhodamine B perchlorate, bromide of ethydium or bromide of        3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide        or di-iodide of        3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium,        fluorescent brightener compound 220 (CAS 16470-24-9/49549-42-5),        fluorescent compound brightener 251 (CAS 16324-27-9),        fluorescent brighter compound 351 (CAS 27344-41-8), chloride of        1.1 2,2′-diethylen-cyanine (CAS: 2402-42-8),        1,1′-diethyl-2,2′-dicarbocyanine iodide (CAS: 14187-31-6),    -   mixtures of these compounds.

According to a preferred embodiment, the photoluminescent organicmolecule/phyllosilicate molecule ratio is from 0.001% to 10% by weightof carbon relative to the phyllosilicate weight, preferably from 0.01%to 5% by weight of carbon relative to the phyllosilicate weight.

According to one embodiment, the hybrid nanoparticle composition is asolid composition, for example a powder.

According to this embodiment, the hybrid nanoparticle compositionpreferably consists essentially of one or more non-swellingphyllosilicates and one or more molecules chosen from photoluminescentcharged organic molecules.

According to this embodiment, the hybrid nanoparticle compositionadvantageously consists of one or more non-swelling phyllosilicates andone or more molecules chosen from photoluminescent charged organicmolecules.

According to another embodiment, the hybrid nanoparticle composition isa fluid composition, such as for example a solution, a suspension, adispersion or a gel.

According to this embodiment, advantageously, the hybrid nanoparticlecomposition comprises one or more non-swelling phyllosilicates, at leastone molecule chosen from photoluminescent charged organic molecules andat least one solvent selected from water, organic solvents, and mixturesof water and solvents miscible with water.

According to one embodiment, the hybrid nanoparticle compositionconsists essentially of one or more non-swelling phyllosilicates, one ormore molecules chosen from photoluminescent charged organic moleculesand at least one solvent chosen from water, organic solvents, andmixtures of water and solvents miscible with water.

According to one embodiment, the composition of hybrid nanoparticlesconsists of one or more non-swelling phyllosilicates, one or moremolecules chosen from photoluminescent charged organic molecules and atleast one solvent selected from water, organic solvents, and blends.water and solvents miscible with water.

The invention also relates to the use of non-swelling phyllosilicatenanoparticles to extract a photoluminescent charged organic moleculefrom an environment, it being understood that when said environment is abiological tissue, it is an isolated or cultivated biological tissue.

The invention also relates to non-swelling phyllosilicate nanoparticlesfor their medical use for extracting a photoluminescent charged organicmolecule from an individual or an animal contaminated with such amolecule.

Another object of the invention concerns a method for extracting aphotoluminescent charged organic molecule from an environment in whichthe photoluminescent charged organic molecule is present, this methodcomprising at least the following steps:

-   -   (1) providing a suspension (b) of non-swelling phyllosilicate        nanoparticles,    -   (2) contacting the suspension (b) and the environment, it being        understood that when said environment is a biological tissue, it        is an isolated or cultivated biological tissue.

The method of the invention has the advantage of allowing the formationof the composite directly from a photoluminescent organic moleculewithout requiring functionalization of this molecule or of thephyllosilicate nanoparticle by metal groups or by other linking agents.The formation of the composite is based on the adsorption of the chargedorganic molecule on the non-swelling phyllosilicate. This method may beimplemented in an aqueous medium. It may be implemented from acomposition of mineral nanoparticles with different photoluminescentmolecules, without it being necessary to form organic/inorganic hybridprecursors prior to the production of the nanoparticles. This proceduregives the method of the invention more flexibility than some previousmethods for the preparation of various photoluminescent materials.

Surprisingly, the inventors have observed that non-swellingphyllosilicate particles, of nanometric size, have a high ability toadsorb photoluminescent organic molecules insofar as the latter arecarrying charges. The very strong adsorption of the photoluminescentorganic compounds on the nanofillers makes it almost impossible for thephotoluminescent molecules to diffuse into the medium and leads to verystable hybrid compounds. These properties are all the more surprisingsince, comparatively, phyllosilicates of micro-size show a much loweradsorption capacity.

The association of charged organic molecules with lamellar non-swellingminerals makes it possible to obtain an organo-mineral hybrid materialhaving selected photoluminescence properties, which may be varied inintensity and hue.

The non-swelling phyllosilicate nanoparticles used in the method of theinvention have an adsorption capacity of photoluminescent chargedorganic molecules which is much higher than that of natural non-swellingphyllosilicates.

Compared to swelling phyllosilicates such as certain clays, thenon-swelling phyllosilicate nanoparticles used in the method of theinvention exhibit photoluminescence of comparable intensity, with alesser amount of photoluminescent agent. Also, in the case of expensivephotoluminescent agents, the photoluminescence rendering may beidentical to that of a swelling clay composite, with a much lower rawmaterial cost.

In the case where toxic photoluminescent markers are used in thelaboratory, awkward handling may lead to contact with the skin or mucousmembranes of the manipulator, or even ingestion of the product. Acomposition based on phyllosilicate nanoparticles can, by its verystrong adsorption capacity of such molecules, be used to irreversiblyfix such toxic compounds and facilitate their elimination.

In the present description, the expression “between X and Y” isunderstood to include the limits, i.e. the parameter may take the valuesX, Y or any value between X and Y.

The expression “consists essentially of” followed by one or morecharacteristics means that, in addition to the components or stepsexplicitly listed, components or steps that do not significantly modifythe properties and characteristics of the invention may be included inthe method or material of the invention.

Throughout the description, the terms “composite” or “hybrid” are usedequally to denote a mixed organic/inorganic material.

Throughout the description, the term “phyllomineral particle” means anymineral particle having a crystalline structure comprising at least onetetrahedral layer and at least one octahedral layer. It may be forexample phyllosilicates.

When it is indicated that two solvents are miscible, it is meant thatthey are miscible in all proportions when they are at room temperature,i.e. at a temperature ranging from 20° C. to 25° C.

DETAILED DESCRIPTION

The inventors have surprisingly found that a method according to theinvention makes it possible to impart a photoluminescent character to anon-swelling phyllosilicate composition in a simple, rapid, butnevertheless durable manner. Thus, a simple contacting of saidphyllosilicate composition in a photoluminescent solution comprisingions of at least one element chosen from photoluminescent chargedorganic molecules makes it possible to obtain a composition comprisingphotoluminescent phyllosilicate mineral particles. Such a methodaccording to the invention also makes it possible to obtain acomposition of phyllosilicate mineral particles having desiredphotoluminescence properties in the manner of a pigment, which areeasily adjustable in intensity and in shade, which make it possible tocover the entire spectrum of ultraviolet and visible, while remainingstable over time.

The surprising nature of this photoluminescence lies, in particular, inthe fact that with different particles of the silicate mineral particlesaccording to the invention, of micrometric size, a very lowphotoluminescence of the particles is obtained. The durability and theirreversible nature of such an adsorption step, as well as the ease withwhich this adsorption is made possible, remain still unexplained to thisday.

Phyllosilicate Nanoparticles

Phyllosilicates are lamellar minerals widely distributed on the surfaceof the earth. These minerals consist of a stack of layers along thecrystallographic axis c* and are known for their high adsorptioncapacity in the case of some.

Phyllosilicates are constituted by a regular stack of elementary sheetsof crystalline structure, the number of which varies from a few units toseveral thousand units. Among the phyllosilicates (lamellar silicates),the group including talc, mica and smectites is characterized in thateach elementary sheet is constituted by the association of two layers oftetrahedrons located on either side of a layer of octahedra. This groupcorresponds to phyllosilicates 2:1. In view of their structure,phyllosilicates 2:1 are also described as T.O.T.(tetrahedron-octahedron-tetrahedron). Natural talc, which is ahydroxylated magnesium silicate of formula Si₄Mg₃O₁₀(OH)₂, belongs tothe family of phyllosilicates.

The octahedral layer of phyllosilicates 2:1 is formed of two planes ofO²⁻ and OH⁻ ions (in the molar ratio O²/OH of 2/1). On either side ofthis middle layer come two-dimensional networks of tetrahedra, one ofwhose vertices is occupied by an oxygen of the octahedral layer, whilethe other three are by substantially coplanar oxygens.

Some phyllosilicates, such as smectites, are characterized by thepresence of interfoliar spaces between the elementary layers thatcontain water and cations and form a swelling phase of the mineral.Smectites are therefore described as T.O.T. swelling. This exchangeable,swelling phase is not present in the non-swelling phyllosilicates usedin the present invention.

The micas are characterized in particular by the presence ofinterfoliary cations in spaces, called interfoliary spaces, locatedbetween the elementary sheets. Unlike smectites, micas are said to benon-swelling and are characterized by the absence of water molecules ininterfoliar spaces, water molecules implying, in particular, a propertyof swelling of the mineral.

As defined in the scientific publication entitled “Nomenclature ofMicas” by Rieder et al. (The Canadian Mineralogist, 1998, Vol 36, pp41-48), the simplified formula for micas is:1M₂₋₃□₁₋₀T₄O₁₀A₂

in which 1 is an interfolar cation (generally K, Na or Ca, for example);M is generally selected from Li, Fe, Mg, Al or Ti; □ represents avacancy, T is generally selected from Al, Fe (trivalent) or Si, and A isgenerally selected from F and OH in particular.

Micas therefore generally comprise many chemical elements includingsilicon, aluminum or iron in tetrahedral sites (T in the general formulaof Rieder et al.) and lithium, iron, magnesium, potassium aluminum ortitanium in the octahedral sites (M in the general formula of Rieder etal).

The micas are also characterized by an X-ray diffraction linecharacteristic of a (001) plane located at a distance between 9.80 Å and10.30 Å.

Kaolinites also belong to the family of phyllosilicates. Among thephyllosilicates, the group comprising in particular kaolinite andserpentine is characterized in that each elementary sheet is constitutedby the combination of a layer of tetrahedra and a layer of octahedra.The octahedral layer of the phyllosilicates 1:1 is formed of a plane ofO⁻ and OH⁻ ions (in the molar ratio O²⁻/OH of 1/1). Each tetrahedrallayer forms a two-dimensional network of tetrahedra, one of whosevertices is occupied by an oxygen of the octahedral layer, while theother three are formed by substantially coplanar oxygens.

This group corresponds to phyllosilicates 1:1. Given their structure,phyllosilicates 1:1 are also called T.O. type (tetrahedron-octahedron).Like talc and mica, kaolinites are called non-swelling. They arecharacterized by the absence of water molecules and cations in theinterfoliar spaces (spaces located between each elementary sheet).

According to the invention, the term “phyllosilicate particles” meansparticles belonging to the group formed by lamellar silicates, lamellargermanates, lamellar germanosilicates and mixtures thereof.

Advantageously, the invention relates to lamellar silicates.

The phyllosilicates used in the present invention belong to the categoryof non-swelling phyllosilicates.

In the present invention, the term “non-swelling” refers to anyphyllosilicate whose diffraction line (001) is not affected by treatmentby contact with ethylene glycol or glycol, i.e. the interatomic distancecorresponding to the (X-ray) diffraction line (001) does not increaseafter being contacted with ethylene glycol or glycol. Phyllosilicates2:1, with the exception of smectites, are non-swelling, for example talcor other phyllosilicates belonging to the group of micas such asmuscovite. Kaolinites also belong to the category of non-swellingphyllosilicates.

In particular, the composition of phyllosilicate nanoparticles that canbe used in the method of the invention does not exhibit, in X-raydiffraction, a diffraction line characteristic of a plane located at adistance of between 12.00 Å and 18.00 Å, characteristic of a swellingphase.

Advantageously, the non-swelling phyllosilicates used in the presentinvention are selected from synthetic talc, synthetic mica, synthetickaolinites and mixtures thereof.

Advantageously, the non-swelling phyllosilicates used in the presentinvention have one of the following chemical formulas:(SixGe(1−x))₄M₃O₁₀(OH)₂,  (I)

in which:

-   -   x is a real number of the interval [0; 1],    -   M denotes at least one divalent metal having the formula        Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each        index yi representing a real number of the interval [0; 1], and        such that E_(i=1) ⁸yi=1,

or(Aly′M′(1−y))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II)

in which:

-   -   M′ denotes at least one trivalent metal chosen from the group        consisting of gallium and rare earths,    -   y′ is a real number of the interval [0; 1],    -   x′ is a real number of the interval [0; 1],

orAt(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III)

in which:

-   -   A denotes at least one monovalent cation of a metal element        having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), Li        denoting lithium, Na denoting sodium, K denoting potassium, Rb        denoting rubidium, Cs denoting cesium and each wi representing a        real number of the interval [0;1] such that Σ_(i=1) ⁵wi=1.    -   x″ is a real number of the interval [0; 1],    -   M″ denotes at least one divalent metal having the formula        Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each        index ji representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸ji=1,    -   k is a real number in the range [2.50; 2.85]    -   t+2k is a real number of the interval [5.3; 6.0].

Even more advantageously, the non-swelling phyllosilicates used in thepresent invention have at least:

-   -   a phase formed of a stack of elementary sheets of 2:1        phyllosilicate type and of chemical formula Si₄M₃O₁₀(OH)₂, in        which M has the same definition as above, and more particularly        of chemical formula Si₄Mg₃O₁₀(OH)₂, or    -   a phase formed of a stack of elementary sheets of phyllosilicate        type: 1 and of chemical formula Al₂Si₂O₅(OH)₄.

According to another advantageous variant, when the non-swellingphyllosilicates used in the present invention have at least one phaseformed of a stack of elementary sheets of phyllosilicate type 2:1 and ofchemical formula (III), at least one of the following conditions isverified:

-   -   Advantageously, they are free of at least one element chosen        from iron, zinc and manganese. In particular, advantageously, a        phyllosilicate used according to the invention is free of iron.    -   In an advantageous variant of formula (III), t is a real number        of the interval [0.8; 1], k is a real number of the interval        [2.5; 2.6].    -   In another advantageous variant of formula (III), formula (III)        is such that t+2k=6.    -   In an advantageous variant of the formula (III), x″=1, the        compound (III) does not comprise germanium.    -   In an advantageous variant of the formula (III), the        compound (III) may comprise, in octahedral sites, a divalent        metal of formula M″.M″ may therefore be chosen from the group        consisting of magnesium, cobalt and zinc, copper, manganese,        iron, nickel and chromium. In a particularly advantageous        variant of a compound according to the invention, M″ is only        magnesium (M″=Mg). In this case, the compound has the following        formula (IIIa):        At(Si_(x)—Ge(1−x″))₄Mg_(k)O₁₀(OH)₂  (IIIa)    -   In other advantageous variants of a compound (III), M″ comprises        magnesium and at least one other metal such as Mn or Ni.    -   In particular, in an alternative embodiment of a compound (III),        j3 is different from 1. More particularly, in a variant of a        compound (III), said compound is devoid of zinc and is equal to        zero.    -   In particular, in an alternative embodiment of a compound (III),        j6 is different from 1. More particularly, in a variant of the        compound (III), said compound is free from iron and j6 is equal        to zero. In fact, it may be advantageous in some applications to        have compounds devoid of iron or whose iron content is limited.    -   Advantageously and according to the invention, in formula (III),        A denotes at least one chemical element selected from the group        consisting of lithium (Li), sodium (Na), potassium (K), rubidium        (Rb) and cesium (Cs). According to one embodiment, A denotes one        or other of the chemical elements chosen from the group        consisting of lithium (Li), sodium (Na), potassium (K), rubidium        (Rb) and cesium (Cs) (such that w1=1, w2=1, w3=1, w4=1 or w5=1        respectively).

In formula (III), A denotes a metal cation arranged in the interfoliarspaces (between the layers) of said compound, each sheet comprising asuccession of a tetrahedral layer, an octahedral layer and then a secondtetrahedral layer (or a structure of TOT type, T designating atetrahedral layer and O designating an octahedral layer). Thus,advantageously, a compound of formula (III) is organized according to asolid structure formed of sheets superimposed on each other andseparated from each other by at least one space, called interfoliarspace, each cation A being disposed in said interfoliar spaces.

In particular, advantageously and according to the invention, A is anon-exchangeable interfolar cation, i.e. that it is stably and durablyassociated with the structure of synthetic mica. This means, inparticular, that it remains associated with said compound when thecompound is suspended in pure water for example, or in water saturatedwith a cation other than A, such as calcium.

-   -   According to a particularly advantageous variant of a compound        of formula (III), A denotes potassium. In this case, the        compound has the following formula (IIIb):        K_(t)(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂  (IIIb).

According to formula (III), the synthetic mica compound has astoichiometric coefficient t relative to the stoichiometric proportionof A of between 0.30 and 1 (including values), and in particular between0.80 and 1 (including values). The stoichiometric coefficient t isrelated to the stoichiometric proportion of metal M″ whosestoichiometric coefficient is k.

-   -   In an advantageous variant of a compound of formula (III), said        compound is such that t=1 and k=2.5 and has the following        formula (IIIc):        A(Six″Ge(1−x″))₄M″_(2.5)O₁₀(OH)₂  (IIIc))

When, in the above formula (IIIc), A is potassium, no germanium issubstituted for silicon and M″ is magnesium, the compound according tothe invention has the following formula (IIId):KSi₄Mg_(2.5)O₁₀(OH)₂  (IIId)

-   -   In another advantageous variant of a compound of formula (III),        said compound is such that t=0.8 and k=2.6 and has the following        formula (IIIe):        A_(0.8)(Si_(x″)Ge_(1-x″))₄M″_(2.6)O₁₀(OH)₂  (IIIe)

When, in the formula (IIIe) above, A is potassium, no germanium issubstituted for silicon and M″ is magnesium, the compound according tothe invention has the following formula (IIIf):K_(0.8)Si₄Mg_(2.6)O₁₀(OH)₂  (IIIf)

It should be noted that a compound of formula (III) is free of aluminumand fluorine. In particular, advantageously, the phyllosilicatecomposition is also free of at least one element chosen from aluminumand fluorine. Such compositions may be particularly advantageous incertain applications, for example cosmetic applications (in particularwith regard to aluminum).

The non-swelling phyllosilicates used in the method of the invention areimplemented in the form of nanoparticles. Advantageously, nanoparticleswith a dimension ranging from 1 nm to 10 μm are used. Preferably, thephyllosilicate nanoparticles that can be used in the invention have athickness of between 1 nm and 100 nm, and a larger dimension is between10 nm and 10 μm, the thickness and the largest dimension being evaluatedby electron microscopy.

In the present invention, the term “thickness” of the silicate mineralparticles is the smallest dimension of said particles, the size of saidparticles being in the direction c* of the crystalline lattice of saidsilicate mineral particles.

In the present invention, the term “larger dimension” refers to silicatemineral particles, the largest dimension of said particles being in theplane (a, b) of the crystalline lattice of said silicate mineralparticles.

The thickness and the largest dimension of the silicate mineralparticles are measured by observation by scanning electron microscopy(SEM) or by transmission electron microscopy (TEM) according to methodswhich are exposed in the experimental part.

Advantageously and according to the invention, when the particles offormula (I) are used, they have a thickness of between 1 nm and 100 nm,in particular between 5 nm and 50 nm, and a larger dimension between 20nm and 10 μm.

Advantageously, when using nanoparticles of formula (II), they have anaverage size of between 20 nm and 600 nm, as observed by electronmicroscopy.

Advantageously and according to the invention, said synthetic mineralparticles of formula (II) have a thickness of between 1 nm and 50 nm, inparticular between 2 nm and 30 nm, for example of the order of 10 nm.

Advantageously and according to the invention, the larger dimension ofthe nanoparticles of formula (II) is between 10 nm and 600 nm, inparticular between 20 nm and 500 nm and more particularly between 20 nmand 300 nm.

Advantageously, when nanoparticles of formula (III) are used, they havean average size of less than 500 nm, in particular an average size ofbetween 10 nm and 400 nm (for example as observed by electronmicroscopy).

The phyllosilicate particles of the invention when mined in the presenceof a charged organic photoluminescent agent make it possible to form ahybrid phyllosilicate/organic photoluminescent material having intensephotoluminescence.

The inventors have found that the size of the silicate mineral particlesis a primordial factor for allowing such photoluminescence. Thus, theinventors have observed that when a method according to the invention isapplied to particles of natural talc having a thickness greater than 200nm, the thickness of the finest natural talc being between 200 nm and300 nm, a photoluminescence of lower intensity is obtained.

The non-swelling phyllosilicate nanoparticles that may be used in themethod of the invention may be obtained as follows:

Method for Preparing a Talc-Type Phyllosilicate:

In the case of synthetic talc, it is possible to proceed according tothe methods described in applications WO2013/004979 and WO2015/159006.

The application WO2013/004979 describes a method for preparing acomposition comprising synthetic mineral particles, in which a hydrogelprecursor of said synthetic mineral particles is prepared by aco-precipitation reaction between:

-   -   at least one compound comprising silicon, and    -   at least one compound comprising at least one metal element,        said co-precipitation reaction taking place in the presence of        at least one carboxylate salt of formula R₂—COOM″ in which    -   M″ denotes a metal selected from the group consisting of Na and        K, and    -   R₂ is chosen from H and alkyl groups containing less than 5        carbon atoms.

As a compound comprising at least one metallic element, it is possibleto use any metal compound adapted to react in said reaction ofco-precipitation of said hydrogel precursor of said synthetic mineralparticles.

Advantageously, said compound comprising at least one metal element is adicarboxylate salt of formula M (R₁—COO)₂ in which:

-   -   R₁ is chosen from H and the alkyl groups comprising less than 5        carbon atoms and,    -   M denotes at least one divalent metal having the formula        Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each        index yi representing a real number of the interval [0; 1], and        such that Σ_(i=1) ⁸yi=1.

The hydrogel is then subjected to any suitable treatment to obtain saidsynthetic phyllosilicate mineral particles, for example a batch typehydrothermal treatment. For example, the hydrogel is then subjected to ahydrothermal treatment at a temperature between 150° C. and 400° C. toobtain said phyllosilicate particles.

The groups R₁ and R₂ may be the same or different, they may be selectedfrom the group consisting of CH₃—, CH₃—CH₂— and CH₃—CH₂—CH₂—.

Advantageously, the compound comprising silicon comprises any compoundcomprising at least one silicon atom adapted to react in saidco-precipitation reaction of said hydrogel precursor of said syntheticmineral particles. In particular, said compound comprising silicon ischosen from the group consisting of sodium silicates and silicas(silicon dioxides).

Advantageously, sodium metasilicate is used as a compound comprisingsilicon. Advantageously, said precursor hydro gel of said syntheticmineral particles is a silico/germano-metallic hydrogel, of formula(Si_(x)Ge_((1-x)))₄M₃O₁₁, n′H₂O:

-   -   x being a real number of the interval [0; 1],    -   n′ being relative to a number of molecules of water associated        with said silico/germano-metallic hydrogel. Preferably, said        silico/germano-metallic hydrogel has the formula Si₄M₃O₁₁,        n′H₂O. In this case, said silico/germano-metallic hydrogel of        formula Si₄M₃O₁₁, n′H₂O is a silicometallic hydrogel.

The phyllosilicate mineral particles have at least one non-swellingphase formed of a stack of 2:1 phyllosilicate elemental sheets and ofchemical formula (SixGe(1−x))₄M₃O₁₀(OH)₂. In particular, in aparticularly advantageous embodiment of a method according to theinvention, said non-swelling phase may be formed of a stack ofelementary sheets of 2:1 phyllosilicate type and of chemical formulaSi₄M₃O₁₀(OH)₂, and more particularly of chemical formula Si₄Mg₃O₁₀(OH)₂(M then denoting magnesium).

At the end of the hydrothermal treatment, a composition is obtained inthe form of a colloidal solution containing phyllosilicate mineralparticles having at least one non-swelling phase.

At the end of the hydrothermal treatment, a colloidal compositioncomprising synthetic mineral particles in suspension in an aqueoussolution of carboxylate salt(s) is recovered. Said colloidal compositionmay then be subjected to a drying step, after a possible washing stepwith water so as to eliminate at least partly said carboxylate salt(s).Such a washing step comprises at least one washing/centrifugation cycleof said colloidal composition.

Said composition comprising synthetic mineral particles obtained by amethod according to the invention may be dried by any powder dryingtechnique. Advantageously, following said hydrothermal treatment, saidsynthetic mineral particles obtained by lyophilization are dried. Thedrying may also be carried out by means of an oven, for example at atemperature between 60° C. and 130° C., for 1 hour to 48 hours, undermicrowave irradiation, or else by atomization.

In addition, it is possible to subject the composition comprisingsynthetic mineral particles obtained after hydrothermal treatment to ananhydrous heat treatment, in air, at a temperature above 350° C. andbelow the degradation temperature of the synthetic mineral particles.Advantageously, a composition comprising synthetic mineral particlesobtained after hydrothermal treatment is subjected to an anhydrous heattreatment, at a temperature of between 350° C. and 850° C., inparticular between 400° C. and 750° C., and in particular between 450°C. and 600° C., for example for a period of between 30 minutes and 24hours. Advantageously, after said hydrothermal treatment, thecomposition comprising synthetic mineral particles is subjected to ananhydrous thermal treatment. Such a heat treatment or “annealing” allowsa further increase in the crystallinity of the particles obtained.

According to this variant, the method of the invention providesphyllosilicate nanoparticles characterized in that they exhibit, inX-ray diffraction, the following characteristic diffraction lines:

-   -   a plane (001) located at a distance of between 9.40 Å and 9.90        Å;    -   a plane (002) located at a distance of between 4.60 Å and 4.80        Å;    -   a plane (003) located at a distance of between 3.10 Å and 3.20        Å;    -   a plane (060) located at a distance of between 1.51 Å and 1.53        Å,

the intensity of the diffraction line characteristic of a plane (002)being greater than the intensity of the signal corresponding to a plane(020) located at a distance between 4.40 Å and 4.60 Å, and the ratio ofthe intensity of the diffraction line characteristic of a plane (001) tothe intensity of the characteristic diffraction line of a plane (003)being between 0.60 and 1.50.

The application WO2015/159006 describes a method for the preparation ofsimple and fast phyllosilicate nanoparticles, compatible with anexploitation on an industrial scale, producing phyllomineral syntheticparticles of high purity, having a lamellar character, and having a fineparticle size and low dispersion, as well as a crystalline structurevery close to those of natural phyllominerals, especially naturalphyllosilicates, and in particular natural talc. Such nanoparticles maybe used in the method of the invention.

The method for preparing phyllosilicate particles is carried out bysolvothermal treatment of a reaction medium comprising a liquid mediumand containing, in stoichiometric proportions, the constituent chemicalelements of said particles: this solvothermal treatment is carried outcontinuously at a pressure greater than 1 MPa and at a temperature ofbetween 100° C. and 600° C., the reaction medium is circulatedcontinuously in a zone, called a solvothermal treatment zone, of acontinuous reactor with a residence time of the reaction medium in thesolvothermal treatment zone adapted to obtain continuously, at theoutlet of the solvothermal treatment zone, a suspension comprising thephyllosilicate particles.

Preferably, the solvothermal treatment is carried out at a pressure ofbetween 2 MPa and 50 MPa.

The solvothermal treatment may be applied to a precursor gel comprisingthe stoichiometric proportions of the constituent chemical elements ofthe phyllosilicate particles, the transformation of this precursor gelproducing the phyllomineral particles at the end of the solvothermaltreatment.

Advantageously, as a precursor gel, a precursor silico/germano-metallichydrogel is used, and said solvothermal treatment is carried out in theform of a continuous hydrothermal treatment of thissilico/germanometallic precursor hydrogel.

A precursor hydrogel may be obtained as described above according to themethod taught by WO2013/004979.

According to this variant, the phyllosilicate particles that may be usedin the method of the invention and obtained by the method taught byWO2015/159006 exhibit, in X-ray diffraction, the followingcharacteristic diffraction lines:

-   -   a plane (001) located at a distance of between 9.40 Å and 12.50        Å;    -   a plane (003) located at a distance of between 3.10 Å and 3.30        Å;    -   a plane (060) located at a distance of between 1.51 Å and 1.53        Å.

More particularly, the phyllosilicate particles obtained by a methodtaught by WO2015/159006 exhibit, in X-ray diffraction, the followingcharacteristic diffraction lines:

-   -   a plane (001) located at a distance of between 9.40 Å and 12.50        Å;    -   a plane (002) located at a distance of between 4.60 Å and 5.00        Å;    -   a plane (003) located at a distance of between 3.10 Å and 3.30        Å;    -   a plane (060) located at a distance of between 1.51 Å and 1.53        Å.

Method for Preparing a Phyllosilicate of Kaolinite Type:

According to a second variant, the nanoparticles are synthetickaolinites and are prepared by a method described in ApplicationFR15/59125 in which:

-   -   a precursor gel of said synthetic mineral particles of        formula (II) is prepared by a co-precipitation reaction between:        -   at least one salt of a metal selected from the group            consisting of aluminum and M′, M′ being selected from iron,            gallium and rare earths,        -   at least one source of at least one chemical element            selected from the group consisting of silicon and germanium,            said source of said chemical element chosen from the group            consisting of silicon and germanium being chosen from the            group consisting of potassium metasilicate, sodium            metasilicate, potassium metagermanate and sodium            metagermanate,        -   the molar proportion (Aly′M′(1−y′))/(Six′Ge(1−x′)) during            the preparation of said precursor gel being equal to 1,    -   a solvothermal treatment of said precursor gel is carried out at        a temperature of between 250° C. and 600° C. for a duration        chosen so as to make it possible to obtain synthetic mineral        particles of formula (II).

By bringing into contact the above reagents and respecting thestoichiometric proportions of the compound of formula (II) with regardto the molar ratio between aluminum and/or M′ and silicon and/orgermanium (Aly′M′(1−y′))/(Six′Ge(1−x′)), a precursor gel is obtainedwhich makes it possible, after solvothermal treatment, to obtainsynthetic mineral particles of formula (II), which method makes itpossible to obtain a synthetic non-swelling mineral. It is not necessaryto dry the precursor gel before carrying out the solvothermal treatment,but it is not excluded to perform such drying if it is desired todispose or preserve the precursor gel in the form of a powder. Inparticular, it is advantageous to carry out the solvothermal treatmentof said precursor gel without first drying the prepared precursor gel.

The synthetic mineral particles obtained by the method described abovedo not swell in the presence of ethylene glycol or glycol. The synthetickaolinites obtained by this method are therefore non-swelling, likenatural kaolinites, and have zero electrical charge.

Kaolinites are also characterized by high thermal stability. Thesynthetic mineral particles obtained by this method also have a highthermal stability, especially up to 400° C. In particular,advantageously, such a synthetic kaolinite is thermally stable up to450° C. (especially in air).

Advantageously, the synthetic mineral particles obtained by the methoddescribed in application FR15/59125 have, in X-ray diffraction, at leastone diffraction line characteristic of a plane (001) located at adistance of between 7.00 Å and 7.30 Å, especially at a distance ofbetween 7.00 Å and 7.20 Å.

The synthetic mineral particles obtained by the method described inapplication FR15/59125 have, in the mid-infrared, four vibration bandsbetween 3610 cm⁻¹ and 3700 cm⁻¹, representative of the hydroxyl groupextension (—OH) vibrations.

Any reagent containing aluminum, gallium or a metal belonging to therare earth group, capable of allowing the preparation of syntheticmineral particles according to formula (II) (in particular any reagentcapable of being solubilized in a solvent, for example in water or in analcohol) may be used as a source of aluminum or metal M′ in a methoddescribed in application FR15/59125 for the preparation of the compoundsof formula (II). In particular, advantageously, said aluminum salt isselected from the group consisting of aluminum sulphate, aluminumnitrate, aluminum chloride and aluminum phosphate.

More particularly, said aluminum salt is selected from the groupconsisting of aluminum chloride and aluminum nitrate.

In an advantageous variant embodiment of this method for preparing thecompounds of formula (II), M′ denotes at least one trivalent metal (i.e.having at least one oxidation state of 3) chosen from the group formedof iron, gallium and rare earths. In particular, in an alternativeembodiment of this method in which M′ comprises iron, said solvothermaltreatment is carried out continuously and for a period of less than 12hours, in particular less than 6 hours.

More particularly, M′ denotes at least one metal having the formula:Ga_(z(1))Sc_(z(2))Y_(z(3))La_(z(4))Ce_(z(5))Pr_(z(6))Nd_(z(7))Pm_(z(8))Sm_(z(9))Eu_(z(10))Gd_(z(11))Tb_(z(12))Dy_(z(13))H_(z(14))Er_(z(15))Tm_(z(16))Yb_(z(17))Lu_(z(18))

in which each z(i) represents a real number of the interval [0; 1], suchthat Σ_(i=1) ¹⁸z(i)=1

Throughout the text, rare earths are the metals chosen from the groupconsisting of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce),praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium(Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

Advantageously, in the method for producing the compounds of formula(II), a base, and in particular a strong base, is added during thecoprecipitation reaction of said precursor gel. More particularly,advantageously and according to the invention, during theco-precipitation reaction of said precursor gel, a base selected fromthe group consisting of NaOH (sodium hydroxide) and KOH (potassiumhydroxide) is added.

Said solvothermal treatment is carried out for a time allowing syntheticmineral particles to be obtained according to formula (II). The durationof the solvothermal treatment is chosen as a function of the temperatureand the pressure during the solvothermal treatment as well as theconditions under which it is carried out (batch, continuous) andpossibly of the nature of the solvent used. In particular, syntheticmineral particles according to formula (II) may be obtained after a fewminutes, or even after a few seconds of solvothermal treatment. Theduration of the solvothermal treatment is, for example, greater than 10seconds and less than 6 hours, and for example less than 1 hour in thecase of continuous preparation. In particular, advantageously, saidsolvothermal treatment is carried out for a period of less than 48hours, especially less than 24 hours. More particularly, saidsolvothermal treatment is carried out for a period of less than 20hours, in particular less than 18 hours and, for example, less than 12hours.

The solvothermal treatment may be carried out in a sealed closed reactor(autoclave for example) or continuously. In a particularly advantageousvariant, said solvothermal treatment may be carried out continuously, inparticular by using a continuous reactor. Any known continuous reactormay be used in a method as described above. Thus, advantageously, saidcontinuous reactor is a constant volume continuous reactor. In aparticularly advantageous variant of this method, a continuous reactorchosen from the group consisting of piston reactors (or piston-type flowreactors) is used. These may be, for example, tubular reactors in whichthe flow of the reaction medium is carried out in a laminar, turbulentor intermediate regime. In addition, it is possible to use anycontinuous cocurrent or countercurrent reactor with respect to theintroduction and bringing into contact of the various compositionsand/or liquid media contacted in this method.

The solvothermal treatment of a reaction medium comprising saidprecursor gel is carried out in a solvothermal treatment zone of thereactor at a temperature adapted to allow said synthetic particles to beobtained, in particular as a function of the pressure and the durationof the solvothermal treatment. Advantageously and according to theinvention, said solvothermal treatment is carried out at a temperatureof between 280° C. and 450° C. More particularly, advantageously andaccording to the invention, said solvothermal treatment is carried outat a temperature of between 290° C. and 420° C., in particular between290° C. and 400° C., and in particular between 295° C. and 375° C.

The solvothermal treatment of a reaction medium comprising saidprecursor gel is carried out in a solvothermal treatment zone of thereactor at a pressure suitable for obtaining said synthetic particles,depending, in particular, on the temperature and the duration of thesolvothermal treatment. Advantageously, said solvothermal treatment iscarried out at a pressure greater than 1 MPa. More particularly, saidsolvothermal treatment is carried out at a pressure of between 2 MPa and50 MPa, in particular between 8 MPa and 40 MPa, and in particularbetween 22 MPa and 30 MPa. This is, in particular, the saturated vaporpressure at the temperature at which the solvothermal treatment iscarried out, if the solvent is water. In a particularly advantageousvariant of this method, said solvothermal treatment is carried out in anaqueous medium. It is then a hydrothermal treatment. Water may be usedas a sole solvent or diluent or mixed with any other fluid.

Advantageously and according to the invention, it is possible to use aschemical formula for said precursor gel, the following chemical formula(Ilbis):2(Aly′M′(1−y′))2(Six′Ge(1−x′))(5−ε)O(4+2ε)OH  (Ilbis),

in which ε is a real number of the interval [0; 5].

Another chemical formula is sometimes also used to define said precursorgel, it is the following formula: (Aly′M′(1−y′))₂ (Six′Ge(1−x′))₂O₇, orwith regard to a precursor gel for the preparation of a synthetickaolinite with x′=1, y′=1: Al₂Si₂O₇.

Method for Preparing a Phyllosilicate of Mica Type:

According to a third variant, the nanoparticles are synthetic micas andare prepared by a method described in application FR15/59129, comprisingthe following steps:

1/ Preparation of a Precursor Gel of a Compound of Formula (III)

The precursor gel of a compound of formula (III) may be prepared by acoprecipitation reaction involving, as a reagent, at least one source ofsilicon and/or at least one source of germanium chosen from the groupformed of potassium metasilicate and potassium metagermanate, and atleast one metal salt of a divalent metal M″, M″ denoting at least onedivalent metal having the formulaMg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each index jirepresenting a real number of the interval [0; 1], and such that Σ_(i-1)⁸ji=1, (Mg denoting magnesium, Co denoting cobalt, Zn denoting zinc, Cudenoting copper, Mn denoting manganese, Fe denoting iron, Ni denotingnickel and Cr denoting chromium) and each ji representing a real numberof the interval [0; 1], such that Σ_(i-1) ⁸ji=1.

This coprecipitation reaction makes it possible to obtain a precursorgel exhibiting the stoichiometry of a synthetic mica corresponding toformula (III).

The precursor gel is prepared by a coprecipitation reaction implementedfrom:

-   -   an aqueous solution in which at least one metal salt of a        divalent metal M″ is dissolved, for example an aqueous solution        of a metal sulphate (M″SO₄),    -   a solution of sulfuric acid (H₂SO₄), and    -   an aqueous solution of potassium metasilicate or an aqueous        solution of potassium metagermanate, or a mixture of these two        solutions in the molar proportions x″/(1−x″).

The molar proportion (Six″Ge(1−x″)/M″ during the preparation of thisprecursor gel is in the range [2/1.425; 1.6], and in particular in therange [2/1.3; 1.6].

The preparation of this precursor gel is carried out according to thefollowing protocol:

The solution comprising at least one metal salt is mixed with thesulfuric acid solution and the aqueous solution of potassiummeta-silicate and/or potassium metagermanate is then added thereto; theprecursor gel is formed instantly.

The suspension obtained comprising the precursor gel may be stirred atroom temperature (for example at 22.5° C.) for 5 to 30 minutes and thensubjected to several cycles of washing and centrifugation or may bedirectly subjected to these cycles of washing and centrifugation.

The precursor gel may also be recovered after centrifugation (forexample between 3000 and 15000 rpm, for 5 to 60 minutes) and removal ofthe supernatant (potassium sulfate solution) and washing withdemineralized water (for example three washes and successivecentrifugations).

The precursor gel washed and separated from the solution comprisingpotassium sulphate is then subjected to a solvothermal treatment asobtained at the end of the last centrifugation or possibly after havingbeen dried (for example in an oven or by freeze-drying).

At least one hydroxide of formula AOH is then added to said precursorgel so that the molar proportion A/M″ is at least equal to t/k.

A suspension of precursor gel and hydroxyl AOH is thus obtained.

2/—Solventothermal Treatment of Said Precursor Gel

The precursor gel as previously obtained (after the addition of thehydroxyl AOH) is subjected to a solvothermal treatment at a temperatureof in particular between 300° C. and 600° C.

In a first variant, the solvothermal treatment of the precursor gel iscarried out in a closed reactor.

To do this, the precursor gel is placed in a reactor/autoclave that isplaced inside an oven at a predetermined reaction temperature (setbetween 300° C. and 600° C.), during the entire duration of thesolvothermal treatment.

In advance, the liquid/solid ratio may be adjusted to a value of between2 and 80, in particular between 5 and 50 (the quantity of liquid beingexpressed in cm³, and the amount of solid, in grams, and denoting theamount of gel dry only).

In particular, it is preferable to place the reactor or the autoclaveunder the conditions of temperature and pressure of the solvothermaltreatment less than 6 hours, especially less than 3 hours, and moreparticularly less than one hour, after adding the hydroxide of formulaAOH to the precursor gel.

During the hydrothermal treatment, the precursor gel gradually acquiresa gelatinous consistency. The composition obtained at the end of thesolvothermal treatment has an observable crystallinity in X-raydiffraction, this crystallinity increasing with the duration of thesolvothermal treatment and resulting in the corresponding diffractogramsby the rapid appearance of characteristic lines which are refined andintensify rapidly during treatment.

At the end of this solvothermal treatment, a composition is obtainedcomprising mineral particles of synthetic mica according to formula(III) in suspension in a solution, in particular an aqueous solution. Atthe end of this solvothermal treatment, the composition contained in thereactor is recovered by centrifugation (between 3000 and 15000 rpm, for5 to 60 minutes) and then removal of the supernatant.

The composition comprising mineral particles recovered after the lastcentrifugation can then be dried:

-   -   in an oven at a temperature between 60° C. and 130° C., for 1 to        24 hours, or,    -   by lyophilization, for example in a freeze-dryer of the CHRIST        ALPHA® 1-2 LD Plus type, for 48 hours at 72 hours,    -   or by atomization.

In a second variant, the solvothermal treatment of the precursor gel iscarried out continuously.

In a method in which the solvothermal treatment is carried outcontinuously, a reactor 15 for preparing mineral particles of a compoundaccording to the invention is used continuously (as illustrated in FIG.3 ) comprising:

-   -   a first portion 11 of conduit in which a first aqueous solution        20 comprising the precursor gel is introduced,    -   a second portion 12 of conduit in which a second aqueous        solution 21 comprising at least one hydroxide of formula AOH        (KOH for example) is introduced,    -   a third portion 13 of conduit disposed after the first conduit        portion 11 and the second conduit portion 12 and extending to an        inlet 9 of a reaction chamber 16, the first conduit portion 11        and the second portion 12 of conduit joining at a point 17 from        which the third portion 13 of conduit begins,    -   a reaction conduit 14 extending from the inlet 9 into the        reaction chamber 16, and after the third conduit portion 13.

A peristaltic pump 18 continuously feeds the first portion 11 of conduitwith the first aqueous solution 20 contained in a reservoir 30 understirring. A second peristaltic pump 19 continuously feeds the secondportion 12 of conduit with the second aqueous solution 21 contained in areservoir 31 with stirring.

In order to control the temperature within the reaction conduit 14, thereaction chamber 16 is an oven comprising a heating sleeve comprisingceramic material resistors. The reaction conduit 14 is in the generalshape of a coil wound in multiple turns inside the heating sleeve, untilit leaves the latter through an outlet 8 constituting the outlet of thereaction chamber 16.

The mixture inside the third portion 13 of the conduit is close toambient temperature. The third portion 13 of conduit is optional, thepoint 17 and the input 9 may be combined. In the embodiment as shown inFIG. 3 the third portion 13 of conduit has, for example, a length ofbetween 10 cm and 20 cm.

The total residence time in the device for preparing synthetic mineralparticles by a method according to the invention is less than 30minutes, and in particular less than 15 minutes or even less than 5minutes or of the order of one minute.

In addition, it is possible to introduce other solutions and, inparticular, to adjust the amount of solvent at different levels of thedevice, for example using inputs 4, 5 located before the solvothermaltreatment zone, the inlet 4 being located before the point 17, the inlet6 being located at the level of the solvothermal treatment zone, theinlet 7 being located after the exit of the solvothermal treatment zoneand before the exit of the suspension obtained.

A pressure regulator 2 is disposed downstream of the reaction chamber 16in connection with a fifth portion 10 of conduit extending from theoutlet 8 of the reaction conduit 14 and the reaction chamber 16 to acontainer 25 in which is recovered a suspension comprising the mineralparticles obtained.

The closure of a valve 32 interposed on the fifth portion 10 of conduitmakes it possible to circulate the suspension obtained at the outlet 8of the reaction conduit 14 in a circuit 33 which makes it possible topass this suspension through a porous sinter 34 designed to retain theparticles and allow their recovery. The porous sinter 34 is immersed inan ice bucket 35 for cooling the suspension leaving the reactor. In thiscase, valves 36 and 37 disposed on the branch circuit 33 are open. Theporous sinter 34 is chosen to retain the synthesized mineral particlesby separating them from the liquid medium which carries them. Thesintered material is, for example, made of stainless steel 316L, with apore size of 50 μm. When the porous sinter is clogged with mineralparticles, it suffices to open the valve 32 and to close the valves 36and 37 to directly recover the suspension in the container 25, thissuspension being cooled through the ice container 35, then washed andcentrifuged several times to recover the mineral particles which canthen be dried, for example in an oven. In another variant (not shown),it is of course also possible to provide several sinters in parallel,which allows the suspension obtained at the outlet of the reactionconduit 14 to be directed to another sinter as soon as the preceding oneis clogged by the mineral particles.

Alternatively, in the case where a solution comprising the precursor geland the hydroxyl AOH is initially prepared, the same and only portion ofthe conduit replaces the first conduit portion 11 and the second conduitportion 12. In another variant, it is also possible for the reservoir 30to contain a solution comprising the precursor gel and for the reservoir31 to contain the hydroxide AOH.

In each case, it is important to control the dilution of the precursorgel introduced into each portion of conduit and into the reactionconduit 14 so as to allow continuous circulation of the reaction mediumin the reaction conduit 14, and in all the conduits supplying saidprecursor gel composition to the inlet 9 of the reaction chamber 16. Theconcentration of precursor gel in said precursor gel compositionintroduced at the inlet of the reaction chamber 16 is advantageouslybetween 10⁻³ mold and several mold, for example of the order of 0.01mol./L. This concentration is much lower than the concentrations used inthe methods for the preparation of synthetic mineral particles such asphyllosilicates of the prior art.

The solvothermal treatment carried out in the reaction conduit 14 is asolvothermal treatment which may, in particular, be carried out undersupercritical or subcritical conditions, and, in particular, underhomogeneous subcritical conditions. Thus, it is possible to choose thetemperature and the pressure at which this solvothermal treatment iscarried out so that the precursor gel composition introduced at theinlet of the reactor, and in particular the solvent(s) it comprises isunder supercritical conditions or under homogeneous subcriticalconditions, i.e. above the liquid-gas equilibrium curve of the solvent,and so that the solvent is present at the liquid state and not in theform of a liquid-gas mixture or gas alone.

At the end of this solvothermal treatment, a suspension is obtainedcomprising inorganic particles in solution, in particular in aqueoussolution. At the end of this solvothermal treatment, the suspensionobtained is recovered by filtration, for example by means of a ceramicsinter, or else by centrifugation (between 3000 and 15000 rpm, for 5 to60 minutes) then elimination of the supernatant.

The composition comprising recovered mineral particles may optionally bewashed with water, in particular with distilled or osmosis water, forexample by carrying out one or two washing/centrifugation cycles.

The composition comprising mineral particles recovered after the lastcentrifugation may then be dried:

-   -   in an oven at a temperature between 60° C. and 130° C., for 1 to        24 hours, or,    -   by lyophilization, for example in a CHRIST ALPHA® 1-2 LD Plus        lyophilizer, for 48 hours to 72 hours, by microwave irradiation,    -   by atomization,        or by any other powder drying technique.

The mineral particle composition (b) derived from a solvothermal method,advantageously chosen from those described above for each of the 3variants (talc, kaolinite, mica), may be used in the form of an aqueoussuspension directly derived from the solvothermal method, possibly withthe addition of one or more cosolvents. The inorganic particles may alsobe dispersed in an organic solvent, after drying the aqueous phase, foruse in the method of the invention. Among the organic solvents that maybe used, mention may be made of alcohols or polyols, such as, forexample, methanol, ethanol, glycerol or ketones, such as propanone or2-butanone.

Advantageously, the mineral particle composition (b) is in the form ofan aqueous suspension or a hydro-organic suspension comprising assolvent a mixture of water and one or more co-solvents such as alcoholsor polyols, such as for example methanol, ethanol, glycerol, ketonessuch as propanone or 2-butanone.

Even more advantageously, the mineral particle composition (b) that canbe used in the method of the invention is an aqueous suspension.

Photoluminescent Charged Organic Molecule

According to the invention, photoluminescent molecule is understood tomean a molecule which absorbs in the ultraviolet range, either at awavelength ranging from 200 to 380 nm, or in the visible range (i.e. ata wavelength between 380 and 780 nm), and re-emits the energy absorbedin light form.

Photoluminescent charged molecule mixtures may be used.

The photoluminescent molecules of the invention advantageously have aplanar character, i.e. that at least part of these molecules is flat orsubstantially flat.

By substantially planar is meant any molecule (or fragment of molecule)for which the deviation of one or more atoms is less than 15 picometerswith respect to the mean plane, this deflection being able to bemeasured by X-ray diffraction (measurement carried out on a monocrystal)or as a result of a molecular modeling in the case where obtaining asingle crystal of said molecule could not be possible, using software i)Accelrys (Discovery Studio Modeling Environment, Release 4.0, San Diego:Accelrys Software Inc., 2013) and ii) Discovery Studio Visualizer 4.0(DSV).

By molecule comprising a planar part is meant a molecule of which atleast 4 atoms connected to each other are placed in the same plane.

Molecule comprising a planar part, advantageously means a molecule ofwhich at least 4 atoms form a structure comprising at least twoconjugated multiple bonds.

By multiple bonds is meant bonds selected from double bonds (e.g. C═C orN═N) and triple bonds.

According to one embodiment, the molecule comprising a planar partcomprises at least 5 atoms which form a structure comprising at leasttwo conjugated multiple bonds and at least one atom carrying an electronpair.

According to one embodiment, the molecule comprising a planar partcomprises at least 6 atoms which form an aromatic ring.

The polycyclic aromatic molecules form a conjugate πl system and areplanar. The conjugated aromatic heterocyclic molecules generally have asubstantially flat structure.

By charged molecule is meant:

-   -   i) any molecule (or fragment of molecule) carrying at least one        ionizable or ionized function        -   in the form of a salt with a metal preferably selected from            alkali metals, alkaline earth metals, transition metals and            rare earths or mixtures thereof, or        -   in the form of an organic salt such as the salts of            carboxylic acids or of sulphonic acids;

As well as

-   -   ii) any molecule (or fragment of molecule) carrying at least one        ionized heteroatom (N, P, S, O), such as for example berberine        or methylene blue,    -   iii) any molecule carrying one or more ionizable or ionized        functions and comprising one or more ionized heteroatoms).

By ionizable function is meant a carboxylic acid function, phosphonicacid, a C—SO₃H function, as well as phenols. The charged fragment of themolecule may optionally be distinct from the chromophore moiety of saidmolecule.

Among the photoluminescent molecules that may be used in the method ofthe invention, mention may be made of:

Rhodamine B or[9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]diethylammoniumchloride—or any other form of Rhodamine B such as, for example,Rhodamine B perchlorate, ethidium bromide or bromide of3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or3,8-diamino-5-[3-(diethylmethylammonio) propyl]-6-phenylphenantridiniumiodide, the fluorescent brightener compound 220 (CAS16470-24-9/49549-42-5), the fluorescent compound brightener 251 (CAS16324-27-9), the fluorescent brightener compound 351 (CAS 27344-41-8),the chloride of 1,1′-diethyl-2,2′-cyanine (CAS: 2402-42-8),1,1′-diethyl-2,2′-dicarbocyanine iodide (CAS: 14187-31-6).

The solution of at least one photoluminescent charged organic moleculethat can be used in the method of the invention may consist of asolution of a photoluminescent charged organic molecule alone, or of amixture of photoluminescent molecules in a solvent.

The photoluminescent organic molecule usable in the present invention ischarged, and the ionic or ionizable function of said molecule may be ofcationic or anionic nature.

Each photoluminescent molecule is chosen according to the desiredresult, in terms of the chemical composition of the photoluminescentphyllosilicate composition and in particular of the type ofphotoluminescence expected.

It is also possible to use mixtures of photoluminescent chargedmolecules and colored charged molecules in the visible range.

When a mixture of photoluminescent molecules and colored molecules inthe visible range is used, advantageously, the colored molecule(s) arecharged and flat or substantially flat.

Among the visible colored molecules that can optionally be used in themethod of the invention, mention may be made of:

Anthocyanins: Anthocyanins belong to the family of polyphenols and areresponsible for the coloring of the leaves, stems and roots of manyplant species, for example in the case of the violet color of redgrapes. Among the anthocyanins are: pelargonidine, cyanidine, peonidine,delphinidine, petunidine, malvidine, apigenidine, luteolidine,tricetinidine, 6-hydroxypelargonidine, 6-hydroxy cyanidine, 6-hydroxydelphinidine, europinidine, rosinidine, capensinidine, pulchelidine,hirsutidine, 5-methylcyanidine, fisetinidine.

These anthocyanin compounds may be used in simple form or in the form ofglycosides which are the most frequently encountered form in nature.

Mention may also be made, among the visible colored molecules that maybe used in the method of the invention, of melanins (such as eumelaninand pheomelanin), for example those present in the ink of certaincephalopods such as cuttlefish and melanin derivatives, includingsynthetic analogues.

Mention may also be made of humic acids which are derivatives ofpolyphenols bearing ionizable carboxylic acid functions, and ionized atcertain pH. These are high molecular weight, negatively charged polymersresulting from a method of oxidative condensation of phenolic compoundsand bound to amino acids, peptides, and polysaccharides.

An example of a structure of the humic acid type is illustrated below:

Mention may also be made, among the visible colored molecules that maybe used in the method of the invention: methylene blue or3.7bis(dimethylamino)phenothiazine-5-ylium chloride, crystal violet ortris(4(dimethylamino)phenyl chloride)methylium, congo red orbenzidinediazo-bis-1-naphthylamine-4-sulphonic acid, porphyrins, inparticular porphine, eosin γ or bromofluorescent acid, eosin B orimperial red, thiazole orange or ptosylate ofmethyl-4-[(3-methyl-2(3H)-benzothiazolylidene)methyl]quinolinium, acidblack 1 (CAS 1064-48-8) and acid black 2 (CAS 8005-03-6), Eriochromeblack T or(4Z)-4-[(1-hydroxynaphthalen-2-yl-hydrazinylidene)-7-nitro-3-oxo-naphthalene-1-sulphonate,blue patent V (CAS 20262-76-4 and 3536-490).

According to one variant of the invention, provision may be made to use,as a colored organic charged molecule, an extract, in particular anaqueous extract of a colored vegetable fraction, such as for example anaqueous fruit extract such as grape, elderberry, pomegranate, acai, anaqueous extract of flower petals such as poppies, mauves or peonies, anaqueous extract of vegetables such as beet, an aqueous extract of acolored animal fraction, such as a extract of cochineal . . . , aproduct derived from these plant and animal extracts, such as wine thatis derived from grape juice by alcoholic fermentation.

The solution (a) of at least one photoluminescent charged organicmolecule for use in the method of the invention may be an aqueoussolution, an organic solution or a hydro-organic solution. Among theorganic solvents that may be used, there may be mentioned methanol,ethanol, glycerol, ketones such as propanone or 2-butanone.

Advantageously, the solution of at least one photoluminescent chargedorganic molecule that may be used in the method of the invention is anaqueous solution or a hydro-organic solution comprising as solvent amixture of water and one or more co-solvents such as alcohols orpolyols, such as, for example, methanol, ethanol, glycerol, ketones suchas propanone or 2-butanone.

Even more advantageously, the solution of at least one photoluminescentcharged organic molecule that may be used in the method of the inventionis an aqueous solution.

Preparation of the Composition of Photoluminescent Nanoparticles

The method of the invention comprises contacting, in a monophasicsolvent medium, at least one photoluminescent charged organic moleculeand non-swelling phyllosilicate nanoparticles having a thickness of 1 nmto 100 nm, and a larger dimension of 10 nm to 10 μm.

According to the invention, the term “monophasic solvent medium” means asolvent or a mixture of solvents miscible with each other. Such solventsform only one phase and do not separate after remaining withoutstirring. Miscibility is evaluated at room temperature.

Advantageously, a solvent or a mixture of solvents is chosen in whichthe photoluminescent charged organic molecule is soluble and in whichthe non-swelling phyllosilicate nanoparticles are dispersible.

Advantageously, the solvent chosen is a mixture of water and one or moreco-solvents such as alcohols or polyols, for example methanol, ethanol,glycerol or ketones such as propanone or 2-butanone.

Even more advantageously, the solvent used in the method of theinvention is water.

According to a first embodiment, the two components, thephotoluminescent charged organic molecule and the non-swellingphyllosilicate nanoparticles, are introduced in powder form in amonophasic solvent medium and dispersed with stirring.

According to a second embodiment, the photoluminescent charged organicmolecule is implemented in the form of a solution (a) in at least onesolvent, the non-swelling phyllosilicate nanoparticles are introduced inpowder form into solution (a). The non-swelling phyllosilicatenanoparticles are dispersed in the solution (a) with stirring.

According to a third embodiment, the non-swelling phyllosilicatenanoparticles are used in the form of dispersion (b) in at least onesolvent and the photoluminescent charged organic molecule is introducedin powder form into dispersion (b).

According to a fourth embodiment, which is the preferred embodiment, thephotoluminescent charged organic molecule is provided as a solution (a)in at least one solvent, the non-swelling phyllosilicate nanoparticlesare provided in the form of a suspension (b) in at least one solvent,then the solution (a) and the suspension (b) are brought into contact.

In a method according to the invention, the duration of step (iii)during which the composition (b) comprising phyllosilicate mineralparticles is brought into contact with the solution (a) comprising atleast one photoluminescent charged organic compound, the concentrationof each photoluminescent charged organic compound in thephotoluminescent solution (a) and the temperature at which this steptakes place, are adapted to allow fixation of the photoluminescentcharged organic compound on the phyllosilicate nanoparticles andtherefore a photoluminescence of the composition of phyllosilicatenanoparticles.

Advantageously and according to the invention, the time during whichsaid phyllosilicate nanoparticle composition (b) is brought into contactwith the photoluminescent solution (a) is sufficient to obtainphotoluminescent phyllosilicate particles. A duration of a few secondsmay be sufficient in certain cases to obtain good photoluminescence,especially at a sufficient temperature and in the presence of asufficient photoluminescent compound concentration and optionally bysubjecting the mixture comprising the photoluminescent solution (a) andthe composition of phyllosilicate nanoparticles (b) under ultrasound.Advantageously and according to the invention, the time during which thecomposition of phyllosilicate nanoparticles (b) is brought into contactwith a photoluminescent solution (a) is greater than 2 seconds,especially between 2 seconds and 7 days, in particular between 2 secondsand 24 hours, for example between 5 minutes and 1 hour.

Advantageously, the concentration of the photoluminescent chargedorganic molecule present in the photoluminescent solution (a) is chosentaking into account, in particular, the temperature, the duration ofcontact with the phyllosilicate nanoparticle composition (b), the natureof the composition of phyllosilicate nanoparticles (b) and the nature ofthe photoluminescent charged organic molecule (s) used (s) used, saidconcentration being chosen so as to be sufficient to allow the obtainingof photoluminescent phyllosilicate mineral particles. For carrying outthe method of the invention, a solution (a) of at least onephotoluminescent charged organic molecule of concentration ranging from0.1 mmol/L to 0.1 mol/L is advantageously used.

The photoluminescent compound adsorption step may be carried out at anytemperature at which the photoluminescent solution is in the liquidstate and making it possible to obtain photoluminescent phyllosilicatemineral particles. Advantageously and according to the invention, thisstep takes place at a temperature of between 5° C. and 100° C. Thecontacting which takes place in this step of a method according to theinvention may for example be carried out at ambient temperature (20° C.to 25° C.) or at a temperature slightly higher than room temperature, inparticular between 30° C. and 90° C. and for example between 40° C. and70° C., depending on the nature of the charged photoluminescent organicmolecule(s) used and particles phyllosilicate minerals, as well as theshade and intensity of the desired photoluminescence.

The photoluminescent compound adsorption step may be carried out with orwithout stirring the photo-luminescent solution (a) in which thecomposition of phyllosilicate mineral particles (b) is added. Forexample, it is possible to agitate only a few moments manually (forexample using a metal rod) the photoluminescent solution at the time ofadding the phyllosilicate mineral particle composition (b) to thephotoluminescent solution (a), then letting it rest for the remainder ofthe adsorption step. Advantageously and according to the invention, saidphyllosilicate mineral particle composition (b) comprisingphyllosilicate mineral particles is brought into contact with thephotoluminescent solution (a) with stirring, for example by magneticstirring using a magnetic stirrer. For example, a slow stirring rate isgenerally sufficient to allow contact between the chargedphotoluminescent organic molecule(s) and the phyllosilicate mineralparticle composition (b) allowing the production of photoluminescentphyllosilicate mineral particles.

At the end of this step (iii) of the method according to the invention,the composition comprising photoluminescent phyllosilicate mineralparticles may be recovered by elimination of the liquid phase which mayor may not contain photoluminescent molecules. The liquid phase may, forexample, be removed after natural decantation of the compositioncomprising photoluminescent phyllosilicate mineral particles and removalof the supernatant solution or by centrifugation of the suspensioncomprising the photoluminescent composition obtained. The compositioncomprising photoluminescent phyllosilicate mineral particles recoveredmay then be rinsed to remove photoluminescent agents or othernon-adsorbed components on phyllosilicate mineral particles. Thecomposition comprising photoluminescent phyllosilicate mineral particlesrecovered may also be stored and used without rinsing. Thus,advantageously, in a method according to the invention, following thephotoluminescent compound adsorption step, the photoluminescentphyllosilicate mineral particles obtained are rinsed with an aqueoussolution substantially free of photoluminescent charged organiccompound.

At the end of this photoluminescent compound adsorption step (iii)according to the invention, the composition comprising photoluminescentphyllosilicate mineral particles may be conserved or used as is, in theform of an aqueous or organic gel or suspension, or hydro-organic, or bedried so as to remove, at least in part, the solvent, including water,still present. Advantageously and according to the invention, thephotoluminescent phyllosilicate mineral particles obtained after steps(i) to (iii) of the method of the invention are dried, and before orafter any rinsing. This drying may be carried out by any drying meansallowing the elimination of this solvent, in particular of this aqueoussolution. The drying may, for example, be carried out directly in anoven (for example at a temperature of the order of 100° C.), byspraying, by drying through microwave irradiation or by lyophilization.Advantageously, the composition comprising photoluminescentphyllosilicate mineral particles is dried at a temperature of between60° C. and 200° C.

In addition, it is possible to repeat at least once the adsorption step(iii) during which the composition of phyllosilicate mineral particles(b) is brought into contact with the photoluminescent solution (a),either with the same photoluminescent solution, either with aphotoluminescent solution comprising a different photoluminescentorganic compound. In this way, it is possible to modify or shade thephotoluminescence of such a composition to a greater or lesser extent soas to obtain the desired photoluminescence.

Advantageously, the hybrid nanoparticles of the invention have aphotoluminescent/phyllosilicate organic molecule ratio ranging from0.001% carbon to 10% carbon, preferably from 0.01% carbon to 5% carbonby weight of carbon, based on phyllosilicate compound weight.

When the photoluminescent molecule emits in the visible light underultraviolet light, the photoluminescence of a composition comprisingphotoluminescent phyllosilicate mineral particles obtained by a methodaccording to the invention may be visible to the naked eye.

A composition according to the invention has high chemical stability. Inaddition, such compositions may have various photoluminescencemechanisms (fluorescence, phosphorescence), depending on the chemicalnature of the photoluminescent organic compounds attached to thephyllosilicate mineral particles. Compositions comprisingphotoluminescent phyllosilicate mineral particles according to theinvention may be more or less photoluminescent, more or less light ordark and more or less intense.

Extraction of Photoluminescent Compounds

The ability of phyllosilicate nanoparticles to irreversibly bindphotoluminescent charged organic molecules may also be used to extractphotoluminescent compounds, including toxic compounds, from a medium.For example, photoluminescent compounds such as ethidium bromide orpropidium iodide are frequently used in biology as DNA markers. Whensuch compounds are dispersed in an environment: work surface, laboratoryequipment, skin, mucosa, it is desirable to collect them avoiding moresignificant contamination. It is then possible to use an aqueousdispersion of phyllosilicate nanoparticles, which is placed in contactwith the contaminated environment. Charged organic compounds having anaffinity for non-swelling phyllosilicates, these irreversibly fix them.The solid nature of the nanoparticles allows an easier, more efficientand better safe disposal of these organic compounds.

The nanoparticles may also be used for the treatment of aqueouseffluents charged with photoluminescent compounds, such as effluentsfrom the chemical industries, textile industries, leather industries. Inthe event that an individual or an animal has absorbed anphotoluminescent charged organic compound, especially toxic, theabsorption by this individual or animal of an aqueous dispersion ofnanoparticles of phyllosilicates may be used to neutralize in vivo thesetoxic molecules.

Among the charged organic molecules concerned by this application,mention may in particular be made of: ethidium bromide, propidiumiodide.

FIGURES

FIG. 1 shows the X-ray diffractograms of a nanometric talc ( . . . ) andof a hybrid product prepared according to the protocol of Example 1,with two different amounts of Rhodamine B: - - - =0.6 mg Rhodamine B;solid line=12 mg of Rhodamine B. The intensity percentage (%) is plottedas ordinates as a function of distance, expressed in Angstrom, asabscissa.

FIG. 2 shows the particle size of nanoscale talc (sample 1—▪) and thoseobtained after the addition of Rhodamine B in different amounts (sample2—▴: 0.6 mg RhB, sample 3—●: 12 mg RhB). The particle size (in nm) isgiven in ordinates according to the numbers of samples on the abscissa.

FIG. 3 shows a schematic view of a device for implementing a method forpreparing a synthetic phyllosilicate in which the solvothermal treatmentis carried out continuously.

EXPERIMENTAL PART

1—Material and Methods

1.A. Equipment

-   -   Rhodamine B: commercially available from Aldrich under the        reference R6626-25G    -   Natural Talc: it comes from the quarry of Trimouns, near        Luzenac, in the Pyrenees Ariege (France). It was picked up        manually, by on-site selection of the best possible quality of        ore, from the point of view of the mineralogical purity 99% of        talc).    -   Synthetic nanoscale talc: it was manufactured according to the        protocol described in Example 1 of application WO2013/004979.    -   Nanoscale synthesis kaolinite:

A solution of aluminum nitrate is prepared with 37.51 g (0.1 mole) ofaluminum nitrate nonahydrate in 200 ml of pure water.

A solution of potassium metasilicate is also prepared from 29.67 g of anaqueous solution of potassium metasilicate (K₂SiO₃) having a solidscontent of 52% (i.e. 0.1 mole of potassium metasilicate), of 100 ml of 1M potassium hydroxide (KOH) and 200 mL of pure water.

The first solution of aluminum nitrate is added with stirring to thepotassium metasilicate solution and a white precipitate is formedinstantly.

The resulting suspension is stirred for 5 minutes. Three washing cyclesare then carried out with distilled water and centrifugation at 8000 rpmfor 10 minutes at each new centrifugation. These successive washes withelimination of the supernatant solution after each centrifugation makeit possible to eliminate the potassium nitrate formed during theprecipitation reaction of the precursor gel. The precursor gel placed ina closed titanium reactor placed in an oven is then subjected to ahydrothermal treatment at a temperature of 300° C. for 24 hours underthe saturated vapor pressure of the water in the reactor. After coolingto room temperature, the reactor is opened and the suspension obtainedis centrifuged. After centrifugation, a composition comprising particlesof compound of formula Al₂Si₂O₅(OH)₄ is recovered. The composition ofparticles recovered after centrifugation is dried in an oven (120° C.,12 hours) and then ground with mortar. The composition obtained is inthe form of a white powder.

The X-ray diffractogram of this composition has the followingcharacteristic diffraction lines:

-   -   a plane (001) located at a distance of 7.15 Å;    -   a plane (020) located at a distance of 4.46 Å;    -   a plane (110) located at a distance of 4.37 Å;    -   a plane (111) located at a distance of 4.16 Å;    -   a plane (021) located at a distance of 3.80 Å;    -   a plane (002) located at a distance of 3.56 Å;    -   a plane (130) and a plane (201) located at a distance of 2.56 Å;    -   a plane (131) and a plane (200) located at a distance of 2.50 Å;    -   a plane (202) and a plane (131) located at a distance of 2.33 Å;    -   a plane (060), a plane (331) and a plane (331) located at a        distance of 1.49 Å.

The mid-infrared spectrum of the synthetic kaolinite compositionobtained has four 3620 cm⁻¹, 3651 cm⁻¹, 3667 cm⁻¹ and 3693 cm⁻¹vibration bands representative of the hydroxyl group elongationvibrations (—OH) synthetic kaolinite.

Synthetic Nanoscale Mica:

300 ml of an aqueous solution of magnesium sulphate (33.27 g or 0.135mol) and sulfuric acid (120 g of a 0.5 M solution) are prepared.

A solution of potassium metasilicate is then prepared by diluting 59.35g (i.e. 0.2 mol) of an aqueous solution of potassium metasilicate(K₂SiO₃) containing 52% solids in 150 ml of demineralized water. Thissolution of potassium metasilicate is added to the previous solution anda white precipitate is formed instantly.

The resulting suspension is stirred for 5 minutes. Three washing cyclesare then carried out with distilled water and centrifugation at 8000 rpmfor 10 minutes at each new centrifugation. These successive washes withelimination of the supernatant solution ante after each centrifugationmake it possible to eliminate the potassium sulphate formed during theprecipitation reaction of the precursor gel. Finally, the recoveredwhite precipitate is suspended in demineralized water to a final volumeof 500 ml and subjected to ultrasound with magnetic stirring for 10minutes until a homogeneous suspension of white color is obtained ofprecursor gel.

988 mg of hydrated potassium hydroxide (containing 85% of potassiumhydroxide and 15% of water, i.e. 0.015 mole of added pure potassiumhydroxide), previously diluted in 30 ml of demineralized water, are thenadded to the precursor gel, and the suspension obtained is stirredmagnetically for 5 minutes at room temperature (22.5° C.).

The precursor gel placed in a closed titanium reactor placed in an ovenis then subjected to a hydrothermal treatment at a temperature of 300°C. for 24 hours under the saturated vapor pressure of the water in thereactor.

After cooling to room temperature, the reactor is opened and thesuspension obtained is centrifuged. After centrifugation, a compositioncomprising at least 80% by weight of particles of formulaK_(0.3)Si₄Mg_(2.7)O₁₀(OH)₂ is recovered.

The composition of particles recovered after centrifugation is dried inan oven for 12 hours at 120° C. and then ground in a mortar. Thecomposition obtained is in the form of a white powder.

The X-ray diffractogram of the composition of particles of formulaK_(0.3)Si₄Mg_(2.7)O₁₀(OH)₂, thus obtained has the followingcharacteristic diffraction lines:

-   -   a plane (001) located at a distance of 10.15 Å;    -   a plane (002) located at a distance of 5.03 Å;    -   a plane (020) located at a distance of 4.53 Å;    -   (003) and (022) planes located at a distance of 3.34 Å;    -   a plane (131) located at a distance of 2.60 Å;    -   a plane (005) located at a distance of 2.01 Å;    -   a plane (060) located at a distance of 1.52 Å.

The composition is then subjected to an anhydrous heat treatment at 550°C. in an oven for 5 hours. The composition obtained after the anhydrousheat treatment remains white.

The X-ray diffractogram of the composition of particles of formulaK_(0.3)Si₄Mg_(2.7)O₁₀(OH)₂ obtained after an anhydrous heat treatment at550° C.; after the anhydrous heat treatment, the followingcharacteristic diffraction lines:

-   -   a plane (001) located at a distance of 10.24 Å;    -   a plane (002) located at a distance of 5.02 Å;    -   a plane (020) located at a distance of 4.56 Å;    -   (003) and (022) planes located at a distance of 3.37 Å;    -   a plane (131) located at a distance of 2.60 Å;    -   a plane (005) located at a distance of 2.02 Å;    -   a plane (060) located at a distance of 1.52 Å,

I.B. Methods

I.B.1. Syntheses

Example 1: Synthesis of the Hybrid Nanomaterial Composition Based onSynthetic Talc and Rhodamine B

An aqueous solution of Rhodamine B dosed at 1 mg/ml is prepared. Analiquot of this solution (600 μl, i.e. 0.6 mg of Rhodamine B) is addedat ambient temperature to a suspension of 1 g of nanotalc in 100 ml ofpure water. The pink suspension is stirred under sonication for 5 minand then centrifuged at 14000 rpm for 20 min. It is noted that thesupernatant is colorless which reflects the total adsorption of thephotoluminescent compound on the mineral. The pellet consists of a pinkpaste having a strong photoluminescence under UV irradiation (365 nm).This paste can be dried in an oven (60° C. for 12 h) or bylyophylisation or any other drying technique.

Example 2: Synthesis of the Synthetic Kaolinite and Rhodamine b HybridNanomaterial Composition

The same protocol was applied as in Example 1, using the synthetickaolinite whose preparation is detailed above.

Example 3: Synthesis of the Hybrid Nanomaterial Composition Based onSynthetic Mica and Rhodamine B

The same protocol was applied as in Example 1, using the synthetic micawhose preparation is detailed above.

I.B.2. Tests

Characterization—Test No. 1: Adsorption Test:

a) General Protocol

In order to demonstrate the high adsorptivity of synthetic minerals andthe way in which organic molecules interact with talc, variousadsorption tests have been carried out. In a beaker, a mineral is mixedin the form of an aqueous suspension with a photoluminescent compoundpreviously dissolved in water or a solvent. Water can be added to makethe mixture sufficiently liquid. The whole is then stirred and passedunder ultrasound until the mixture is homogeneous and without visibleagglomerate. The final step is to centrifuge the mixture at 9000 rpm forabout 20 minutes. At the end of this, the mineral is found plated in thebottom of the pot surmounted by the supernatant. As a result, if themineral has fully adsorbed the photoluminescent compound, it isphotoluminescent at the bottom of the pot and no photoluminescentmolecule is detected in the supernatant. On the contrary, if it has notadsorbed the photoluminescent compound, the mineral retains its originalcolor and the supernatant contains the photoluminescent molecule. If atthe end of this first centrifugation the photoluminescent molecules arepresent both in the supernatant and in the mineral, this means that themineral has not adsorbed the entire photoluminescent compound. Thesupernatant is then replaced by water in the pot for a secondcentrifugation. This operation makes it possible to see if theadsorption is strong or if the mineral rejects the photoluminescentmaterial (leaching). This centrifugation step is performed as many timesas necessary.

b) Comparison Test of the Adsorbent Capacity of Natural and SyntheticTalc

Firstly, adsorption tests were carried out to compare the adsorbentcapacity of synthetic talc with that of natural talc with respect toRhodamine B (pink, photoluminescent in the orange domain). The latterwas brought into contact with synthetic talc or natural talc in the sameratio of “amount of photoluminescent compound/amount of mineral” for abetter comparison of the results. At the end of the centrifugation, thephotoluminescence of the minerals and the supernatant are compared inorder to evaluate the adsorbent capacity of the mineral.

Different tests having been carried out with uncharged dyes (β-carotene,curcumin, not reported here) have shown negative results in theadsorption test on synthetic talc.

c) Lamellarity Influence Test on the Adsorption Capacity

Various adsorption tests were performed to evaluate the role of minerallamellarity in the adsorption of charged organic photoluminescentcompounds. For this, we used different minerals with three-dimensionalstructure namely silica fume (3D structure), synthetic analcime (3Dstructure) and nanotalc (lamellar structure). At the end of thecentrifugation, the color of the supernatants and minerals is comparedto see if the structure adsorbs the photoluminescent compound. It shouldbe noted that all the adsorption tests were carried out with Rhodamine Bin the same ratio of “amount of photoluminescent compound/amount ofmineral”, according to the protocol of Example 1, to better compare theresults.

Characterization—Tests No. 2: Characterization Methods

a) X-Ray Diffraction

The XRD analyzes were carried out on a device of the D2 Phaser type,from the Bruker company, with a wavelength of 1.54060 Å (λcu) over adiffraction angle range of from 0 to 80 °2θ. Moreover, the study ofdiffractograms made it possible to determine the coherence range of themineral, i.e. the number of TOT sheets stacked along the c* axis withoutany major flaws. This coherence domain was calculated using Scherrer'sformula:

$L = \frac{0.91 \times \lambda}{B \times {\cos(\theta)}}$where L corresponds to the size of the coherent domain (Å), λ to thewavelength of the radiation, B to the width of the peak at half-height(rad) and θ the angle of the diffraction line.

b) Granulometry

The measurements of the particle size of the synthetic talc were carriedout with a Vasco-2 granulometer of Cordouan Technologies, specific forthe detection of nanoparticles. The analysis results correspond to astatistical study comprising 20 measurements with an acquisition time ofone minute per measurement.

I.B. Results

I.B.1. Results of Adsorption Tests

a) Adsorbent Capacity of Synthetic Talc

The results of adsorption tests of natural talc and synthetic talc areas follows: In all cases, it was noted that after switching to thecentrifuge, the mixture which was homogeneous and photoluminescent as awhole has two distinct phases: a photoluminescent talc precipitate atthe bottom of the pot and a more or less photoluminescent supernatant.In the case of natural talc, the supernatant is in each case a littlecolored and photoluminescent, which means that the mineral has notcompletely adsorbed the photoluminescent compound. On the contrary, inthe case of synthetic talc, the supernatant is in each case perfectlycolorless and non-luminescent, which means that the mineral hascompletely adsorbed the photoluminescent compound.

b) Role of Form Factor (Lamellarity) in Adsorption

It has been found that a three-dimensional structure (analcime, silicafume) prevents the photoluminescent compound from adsorbing on themineral. On the contrary, since it has a lamellar structure (nanotalc),the adsorption occurs.

I.B.2. Characterization of the interaction “Synthetic Talc—Rhodamine B”

a) XRD

The XRD results (FIG. 1 ) show that the presence of Rhodamine B on thetalc shifts the position of the line (001) towards the large angles.

b) Granulometry

The particle size results (FIG. 2 ) show that, in the presence ofphotoluminescent compounds, the size of the two populations of talcparticles (natural, synthetic nanotalc) increases.

The invention claimed is:
 1. Method for the preparation of an organic/inorganic hybrid composition comprising mineral nanoparticles functionalized by at least one molecule chosen from photoluminescent charged organic molecules, this method comprising at least bringing into contact, in a monophasic solvent medium, of at least one photoluminescent charged organic molecule and non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm.
 2. Method according to claim 1, which comprises at least the following steps: (i) providing a solution (a) of at least one photoluminescent charged organic molecule in at least one solvent, (ii) providing a suspension (b) of non-swelling phyllosilicate nanoparticles in at least one solvent, (iii) contacting the solution (a) and the suspension (b), the non-swelling phyllosilicate nanoparticles having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm.
 3. Method according to claim 2, which further comprises the following steps: Elimination of the solvent phase, Recovery of the nanoparticles.
 4. Method according to claim 2, wherein the non-swelling phyllosilicates have one of the following chemical formulas: (Si_(x)Ge(1−x))₄M₃O₁₀(OH)₂,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each index yi representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸yi=1, or (Aly′M′(1−y′))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or At(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), each wi representing a real number of the interval [0; 1] such that Σ_(i=1) ⁵wi=1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each index ji representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸ji=1, k is a real number in the range [2.50; 2,85] t+2k is a real number of the interval [5.3; 6,0].
 5. Method according to claim 2, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.
 6. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim
 2. 7. Method according to claim 1, which further comprises the following steps: Elimination of the solvent phase, Recovery of the nanoparticles.
 8. Method according to claim 7, wherein the non-swelling phyllosilicates have one of the following chemical formulas: (Si_(x)Ge(1−x))₄M₃O₁₀(OH)₂,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each index yi representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸yi=1, or (Aly′M′(1−y′))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or At(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), each wi representing a real number of the interval [0; 1] such that Σ_(i=1) ⁵wi−1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each index ji representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸ji=1, k is a real number in the range [2.50; 2,85] t+2k is a real number of the interval [5.3; 6,0].
 9. Method according to claim 7, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.
 10. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim
 7. 11. Method according to claim 1, wherein the non-swelling phyllosilicates have one of the following chemical formulas: (Si_(x)Ge(1−x))₄M₃O₁₀(OH)₂,  (I) in which: x is a real number of the interval [0; 1], M denotes at least one divalent metal having the formula Mg_(y1)Co_(y2)Zn_(y3)Cu_(y4)Mn_(y5)Fe_(y6)Ni_(y7)Cr_(y8); each index yi representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸yi=1, or (Aly′M′(1−y′))₂(Six′Ge(1−x′))₂O₅(OH)₄,  (II) in which: M′ denotes at least one trivalent metal chosen from the group consisting of gallium and rare earths, y′ is a real number of the interval [0; 1], x′ is a real number of the interval [0; 1], or At(Six″Ge(1−x″))₄M″_(k)O₁₀(OH)₂,  (III) in which: A denotes at least one monovalent cation of a metal element having the formula Li_(w1)Na_(w2)K_(w3)Rb_(w4)Cs_(w5), each wi representing a real number of the interval [0; 1] such that Σ_(i=1) ⁵=1, x″ is a real number of the interval [0; 1], M″ denotes at least one divalent metal having the formula Mg_(j1)Co_(j2)Zn_(j3)Cu_(j4)Mn_(j5)Fe_(j6)Ni_(j7)Cr_(j8); each index ji representing a real number of the interval [0; 1], and such that Σ_(i=1) ⁸ji=1, k is a real number in the range [2.50; 2.85] t+2k is a real number of the interval [5.3; 6.0].
 12. Method according to claim 11, in which the non-swelling phyllosilicates are formed of a stack of elementary sheets: of 2:1 phyllosilicate type and of chemical formula Si₄M₃O₁₀(OH)₂, more particularly of chemical formula Si₄Mg₃O₁₀(OH)₂, or of 1:1 phyllosilicate type and of chemical formula Al₂Si₂O₅(OH)₄, or of 2:1 phyllosilicate type and of chemical formula K Si₄Mg_(2,5)O₁₀(OH)₂ (IIId) or K_(0,8)Si₄Mg_(2,6)O₁₀(OH)₂ (IIIf).
 13. Method according to claim 12, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.
 14. Method according to claim 11, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.
 15. Method according to claim 1, in which the photoluminescent organic molecule is chosen from: Rhodamine B, or [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-dialylammonium chloride—or any other form of Rhodamine B such as for example Rhodamine B perchlorate, bromide of ethydium or bromide of 3,8-diamino-1-ethyl-6-phenylphenanthridinium, propidium iodide or di-iodide-iodide of 3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenantridinium, the fluorescent brightener compound 220, the fluorescent brightener compound 251, the fluorescent brightener compound 351, the 1,1′-diethyl-2,2′-cyanine chloride, the 1,1′-diethyl-2,2′-dicarbocyanine iodide, mixtures of these compounds.
 16. Hybrid nanoparticles composition comprising at least one non-swelling phyllosilicate and at least one molecule chosen from photoluminescent charged organic molecules, said organic molecule being adsorbed on the phyllosilicate, this composition being obtainable by the method according to claim
 1. 17. Composition according to claim 16, wherein the ratio of photoluminescent organic molecule to phyllosilicate is from 0.001% of carbon to 10% of carbon, in terms of carbon mass relative to the phyllosilicate weight.
 18. Composition according to claim 16, wherein the ratio of photoluminescent organic molecule to phyllosilicate is from 0.01% of carbon to 5% of carbon, in terms of carbon mass relative to the phyllosilicate weight.
 19. A method for extracting from an environment a photoluminescent charged organic molecule, comprising applying an effective amount of non-swelling phyllosilicate nanoparticles, having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm, thereby forming a hybrid organic/inorganic composition by adsorption of said photoluminescent charged organic molecule to said non-swelling phyllosilicate nanoparticles, wherein when said environment is a biological tissue, the biological tissue is isolated or cultivated.
 20. A method for neutralizing a photoluminescent charged organic molecule absorbed by an individual or by an animal, comprising causing said individual or animal to absorb non-swelling phyllosilicate nanoparticles, having a thickness of 1 nm to 100 nm, and a larger dimension of 10 nm to 10 μm, thereby forming a hybrid organic/inorganic composition by adsorption of said photoluminescent charged organic molecule to said non-swelling phyllosilicate nanoparticles. 